Battle Balls is a parody of Bakugan, a kids TV show and strategy game involving balls and cards. The characters in the game are identical to the real Bakugans. Some fans believe that the game is actually not a parody. Bart and his friends played with them, and Marge suspected that he was doing drugs. In the Simpsons Battle Balls are a Japanese card game based on a cartoon based on an ancient religion based on a candy bar.
The known cards are
Battle Card Digitate
Defense Card Deflector Warp
Dubaki Goji Kick
an unnamed orange ball that uses a drill
an unnamed butterfly
an unnamed snowman that shoots carrots